Heretofore, such as shown in U.S. Pat. No. 4,602,740 dated Jul. 29, 1986, high pressure water blast guns have been provided with a dump conduit for discharging water at low pressure from a dump conduit or nozzle when the high pressure water stream to the high pressure discharge nozzle is interrupted during use upon release of the manual trigger. The dump nozzle or conduit in the '740 patent extends from the valve body in a generally parallel relation to the superjacent high pressure discharge conduit or pipe. The handle is removably connected to the valve body beneath the dump passage and conduit. Thus, a separate dump conduit is connected to the valve body for relief of the high pressure when the valve member communicating with the high pressure supply conduit is opened to provide direct communication between the high pressure water supply conduit and the dump conduit for relieving the high pressure to the discharge nozzle.
U.S. Pat. No. 5,423,348 dated Jun. 13, 1995 shows a high pressure water shut-in gun in which fluid flow is stopped completely upon manual release of the trigger or actuator for the valve mechanism. The '348 patent does not have a dump or high pressure relief outlet for relieving the high pressure water upon release of a manual trigger.